Husqvana 136 won't start

[andrewedmondson]

I haven't used the chainsaw for a year. I drained the petrol and kept it in a shed.

 

It would start and then gradually die at high revs. Then it would only fire up for a few seconds.

 

I checked the cylinder bore and it is OK. Haven't checked the cylinder pressure yet.

 

I replaced the carb diaphragms and needle and cleaned everything.

 

Now it will not start. The petrol tank builds up pressure too.

I cannot blow through the carb petrol inlet pipe using my mouth. Not sure if this is possible though.

 

I replaced the spark plug and there is a good spark. If I put fuel into the cylinder, it fires up.

 

There is no fuel going into the cylinder from the carb.

 

I put the carb into my ultrasonic cleaner but have the same problem.

 

I replaced the fuel pipe and filter last year.

 

Not sure what to try next.

 

Thanks

[EricBradley]

The little rubber grommet into the cylinder will be perished and or split is my educated guess

[EricBradley]

Item 4

 

Husqvarna 136 Parts List and Diagram - (2003-01) : eReplacementParts.com

[spudulike]

If that silicone rubber grommet is OK (generally it isn't), it will be a fuel delivery issue. Make sure the fuel line isn't clamped at the bottom of the airbox by the black plastic plate. It is then worth checking the metering arm height and perhaps lifting it by 0.5 - 0.75mm and see if it helps otherwise pull the H&L screws, get some carb cleaner down them and then screw them back in and reset correctly.

The gauze filter can get a fine scum in it that blocks it so remove it and check under an eye glass to make sure it is clean.

[andrewedmondson]

Thanks for the replies.

 

I'm not sure where this silicone grommet is located.

 

I already sprayed into the needle valves with cleaner.

 

I doused the filter mesh with petrol. Seemed OK but I'll check again.

 

Fuel spurts out of the pipe when it is removed from the carb, under pressure, so it is not blocked.

 

From the diagram, the metering arms seems to be the one that operates the needle valve. I replaced this and the spring. I'll try bending up a little as you say.

 

What causes the pressure inside the tank?

[spudulike]

Generally doing up the fuel cap but also fuel expanding with atmospheric temperature or engine heat.

[adw]

The 136 has a duck bill tank breather so it is quite normal to have a fair pressure in the tank, you will always get a jet of fuel from the hose when removed from the carb, it is always best to release the filler cap before removing the hose, if it started prior to you remvig and cleaning the carb and now does not run then i guess it is somthing you have or have not done ( sorry )

[spudulike]

Check the gaskets are in the right order. The thin plastic pumping diaphragm goes next to the main body of the carb with the sealing lattice gasket next to the cover.

 

On the metering section - the thin one with the small metal disk on it goes next to the metal cover with the spacer one going between the thin diaphragm and the main body of the carb.

[andrewedmondson]

Thanks Spud. I had the metering disk the wrong way around. I checked the level of the actuating arm for the needle valve and it is flush with the carb surface, as in the instruction manual.

 

Same problem though. Petrol not reaching the cylinder. Fires up with fuel injected into the cylinder through the plug hole.

 

Should you be able to blow through the petrol carb intake, using your mouth? I can't.

 

I would have thought the ultrasound machine would have dislodged any major blockage.

 

Running out of ideas. Perhaps buying another carb? Cheaper than taking it to a dealer. Also, I don't like to be beaten

[spudulike]

Lift the metering arm a little more - it should hold pressure and only let in fuel when the diaphragm contacts it as the fuel in the metering section is depleted. Try another 0.5mm and see what gives!